User-wearable devices, such as activity monitors or actigraphs, have become popular as a tool for promoting exercise and a healthy lifestyle. Such user-wearable devices can be used, for example, to measure heart rate, steps taken while walking or running and/or estimate an amount of calories burned. Additionally, or alternatively, a user-wearable device can be used to monitor sleep related metrics. User-wearable devices, such as smart watches, can additionally or alternatively be used to provide alerts to a user.